System and method for generator frequency control during UPS power walk-in

Abstract

The present disclosure relates to a system for controlling power walk-in for an uninterruptible power supply (UPS) being switched to receive AC power from an AC generator. The system may have a control system and a power walk-in (PWI) subsystem. The PWI subsystem may be controlled in part by the control system. The PWI subsystem may be configured to control at least one of an input current or an input power of an AC signal being provided by an AC generator during a power walk-in operation to attempt to maintain a minimum frequency of the AC signal from the AC generator during the power walk-in operation.

What is claimed is: 
     
       1. A system for controlling power walk-in for an uninterruptible power supply (UPS) being switched to receive AC power from an AC generator, the system comprising:
 a control system; and 
 a power walk-in (PWI) subsystem controlled in part by the control system, and including: 
 the PWI subsystem configured to control at least one of an input current or an input power of an AC signal being provided by an AC generator during a power walk-in operation to attempt to maintain a minimum frequency of the AC signal from the AC generator during the power walk-in operation in which support of a load is gradually transitioned from AC power generated from a battery of the UPS, to being fully supported by the AC signal being generated by the AC generator. 
 
     
     
       2. The system of  claim 1 , wherein the PWI subsystem further comprises a user settable minimum generator frequency control for enabling a user to set the minimum frequency for the AC signal from the AC generator, which the frequency of the AC signal is not to drop below while the power walk-in operation is being carried out. 
     
     
       3. The system of  claim 1 , wherein the power walk-in subsystem is further configured to determine when the AC generator has assumed an entire amount of the load, and subsequently to continuously monitor the load for an increase in the load to a new load level, and when an increase is detected, to initiate an additional power walk-in operation. 
     
     
       4. The system of  claim 1 , wherein the PWI subsystem is configured to determine if the power walk-in operation can be carried out within a predetermined maximum power walk-in time period. 
     
     
       5. The system of  claim 4 , wherein the PWI subsystem further comprises a user settable maximum power walk-in time control for enabling a user to manually set the predetermined maximum power walk-in time period. 
     
     
       6. The system of  claim 5 , wherein the PWI subsystem is configured to detect when it will not be possible for the power walk-in operation to be carried out within the predetermined maximum power walk-in time period while maintaining the frequency of the AC signal being output from the AC generator at the minimum AC frequency. 
     
     
       7. The system of  claim 5 , wherein the PWI subsystem is further configured to allow the minimum generator frequency to be adjusted when the PWI subsystem has detected that the power walk-in operation will not be carried out within the predetermined maximum power walk-in time period. 
     
     
       8. An uninterruptible power supply (UPS) able to control a power walk-in operation when the UPS is being switched to receive AC power from an AC generator, the UPS comprising:
 a control system; and 
 a power walk-in (PWI) subsystem controlled in part by the control system and configured to control at least one of an input current or an input power of an AC signal being provided by an AC generator during a power walk-in operation to either:
 at least attempt to maintain a minimum frequency of the AC signal from the AC generator during the power-walk-in operation; or 
 ensure that the power walk-in operation occurs within a predetermined maximum power walk-in time period, wherein a load being handled by the UPS is gradually transitioned from AC power generated from a battery of the UPS to being fully supported by the AC signal being generated by the AC generator; and 
 
 the PWI subsystem further including a user settable minimum generator frequency control for enabling a user to set a minimum value for the frequency of the AC signal from the AC generator, which the PWI subsystem attempts to maintain while the power walk-in operation is being carried out. 
 
     
     
       9. The UPS of  claim 8 , wherein the PWI subsystem further comprises a user settable maximum power walk-in time control for enabling a user to set a maximum time period within which the power walk-in operation must be carried out. 
     
     
       10. The UPS of  claim 8 , wherein the power walk-in subsystem is further configured to determine when the AC generator has assumed an entire amount of the load, and subsequently to continuously monitor the load for an increase in the load to a new load level, and when an increase is detected, to continue the power walk-in operation. 
     
     
       11. The UPS of  claim 8 , wherein the PWI subsystem is configured to detect when it will not be possible for the power walk-in operation to be carried out within the predetermined maximum power walk-in time period while maintaining the frequency of the AC signal being output from the AC generator at the minimum AC frequency. 
     
     
       12. The UPS of  claim 11 , wherein the PWI subsystem is further configured to allow the minimum generator frequency to be adjusted when the PWI subsystem has detected that the power walk-in operation will not be carried out within the maximum power walk-in time period. 
     
     
       13. A method for controlling power walk-in for an uninterruptible power supply (UPS) being switched to receive AC power from an AC generator, the method comprising:
 setting a minimum frequency which a frequency of an AC signal from the AC generator is not to drop below; and 
 controlling at least one of an input current or an input power of the AC signal being provided by the AC generator during a power walk-in operation to ensure that a minimum frequency of the AC signal from the AC generator is maintained during the power walk-in operation, wherein support of a load is gradually transitioned from AC power generated from a battery of the UPS, to being fully supported by AC power being generated by the AC generator. 
 
     
     
       14. The method of  claim 13 , further comprising determining if the power walk-in operation can be carried out within a predetermined maximum power walk-in time period. 
     
     
       15. The method of  claim 14 , further comprising detecting when it will not be possible for the power walk-in operation to be carried out within the predetermined maximum power walk-in time period while maintaining the frequency of the AC signal being output from the AC generator at the minimum AC frequency. 
     
     
       16. The method of  claim 15 , further comprising allowing the minimum generator frequency to be adjusted when it is detected that the power walk-in operation will not be carried out within the predetermined maximum power walk-in time period, to ensure that the power walk-in operation can be carried out within the predetermined maximum power walk-in time period. 
     
     
       17. The method of  claim 13 , further comprising determining when the AC generator has assumed an entire amount of the load from the UPS, and subsequently continuously monitoring the load for an increase in the load to a new load level, and when an increase in a level of the load is detected, continuing the power walk-in operation. 
     
     
       18. The method of  claim 14 , wherein the predetermined maximum power walk-in time period comprises a user settable maximum power walk-in time period. 
     
     
       19. The method of  claim 13 , wherein the minimum frequency comprises a user settable minimum frequency.